Forum Discussion

hnguyen_1's avatar
hnguyen_1
Occasional Contributor
14 years ago

Think Time, Master/Slave, etc.

Hi,



1) I was reading up on more load testing information and was told that "If an agent computer has more than 75% CPU utilization, or has less than 10% of physical memory available, it is overloaded." Is this correct? So if I want to simulate 3000 concurrent users, I would need to set up a master/slave configuration for load testing using the network suite? Usually, how many virtual users should be ran from 1 client computer, under what specifications?



2) I read http://msdn.microsoft.com/en-us/magazine/cc188783.aspx#S3, but I still don't understand how 1 virtual user translates to 10 - 15 real users. For example, I have a task for export PDF. I assign that to 1 virtual user, if I run that task for 15 virtual users, that will still be 15 concurrent export PDF at the same point in time, how does it translate to 10 * 15 real user performing the export PDF? So, according to that article, think time should not be present in load tests? How do I verify that my load test simulate real user interaction with the system besides just taking their word for it? Also, I've been reading up on how to create a load test scenario but I still don't know how to apply it to my project. Will someone from SmartBear be able to help me with that?



3) From http://smartbear.com/forums/forum/post/?mode=singleThread&thread=07c628a1-1344-4007-8542-b9f17162c15f, I thought that random think time would be introduced into TestComplete 8.1? How will that affect the reproducibility of the test? Is it better to use start delay if I want the results to be reproducible?


  • AlexanderM's avatar
    AlexanderM
    Staff
    14 years ago

    Hello Huong,





    1) 

    So if I want to simulate 3000 concurrent users, I would need to set up a master/slave configuration for load testing using the network suite?


    It is possible to distribute a Load Test using the RAS utility shipped with TestComplete - you will be able to simulate up to 300 user per PC, so you will need 10 PCs to simulate 300 VUs. But depending on specifics of your task and the specs of your Master PC, this number may appear to be too high for the Master PC to handle. In this case you will need to use the Network Suite feature to simulate the needed load by using several Master PCs.





    Usually, how many virtual users should be ran from 1 client computer, under what specifications?


    There are no standard metrics of this kind - this greatly depends on the task contents and the PC specs. But one PC can't host more than 300 VUs.





    2)

    but I still don't understand how 1 virtual user translates to 10 - 15 real users.


    This is correct when we assume that a virtual user has zero think times, while real users have non-zero think times. And under the equality of these user amounts we actually mean the number of HTTP requests sent per second. For example, 1 VU can send 50 HTTP requests per second, while a real user can emulate only 5 requests per second. So, we get 1 VU = 10 Real Users.





    3)

    TestComplete 8.10 allows setting specific think times for requests, they are not random. To simulate higher load, set think times to zero. To simulate real-world scenarios, set non-zero think times as appropriate.